By Ellise Gasner

Times are positively evolving and the focus on sustainability is being embraced by various industries worldwide.

The Parking industry is fortunate that sustainable parking surface alternatives are readily available, easy to incorporate and affordable. Permeable parking has been the norm for our European neighbours for well over two decades and is now becoming widely incorporated throughout North America.

Changes in municipal taxation regulations have building owners and facility managers looking for ways to increase permeability and reduce their volume of storm water run off.  Surface parking areas are now considered part of a facility’s water management strategy.

Installing permeable paving can eliminate all storm water run off, reducing the need for costly storm water infrastructure and allowing for efficient land usage by eliminating the need for bio swales and infiltration ponds.

Sustainable practices are also defined as best managed practices and technologies that have a longer than usual life span and are low in regular maintenance. Lower costs, both initially and long term, is a bench mark of true sustainability.

True sustainability also encompasses ideas such as lower carbon footprint and reuse capabilities. It would not be fully beneficial if products calling themselves sustainable were manufactured in environmentally harmful factories or if they were difficult and costly to dispose of.

Once there is interest and motivation to include permeable alternatives, the next step is to explore the different product offerings and choose the correct one for the specific needs and applications.

New products are being added regularly to this growing market and the differences amongst the brands are not always easily recognized.

Permeable paving systems include porous concrete and asphalt; unit interlocking pavers, as well as permeable pavers; and flexible plastic porous pavers and grid systems for either gravel paving or grass paving.

The underlying, no pun intended, key to successful results in permeable paving is the base preparation.

Permeable bases are constructed using clear aggregate. The voids amongst the stones allow for storm water to be effectively and efficiently captured and buffered beneath the parking surface. The water is held within the base allowing it to either evaporate into the air or percolate down into the ground, recharging the ground water sources and recharging aquifers. The concept of “management of storm water where it lands” is the basis behind permeable ground surfaces.

Individual municipalities have guidelines and regulations dictating how much storm water must be buffered within the base depending upon the surface area. Permeable bases can be designed and constructed to buffer huge amounts of storm water by altering the depth of the base. Bases can be constructed to contain even a 200 year storm, eliminating the need of ANY additional storm water management technologies. This means no piping, no bio swales, no holding ponds, no catch basins or connection to municipal sewer infrastructure.  The cost savings associated with this reduced focus on storm water infrastructure, as you can imagine, are potentially tremendous, especially initially.

Once the base is prepared according to specific recommended guidelines, the next decision is to choose which product should be installed as a driving/parking surface on top of the infiltration base area to properly support your needs.

There are many questions that should be asked and addressed when choosing the correct permeable product for an individual location. 

• What weight load needs to be supported?
• What are the regular area temperatures of the location? Extreme heat? Extreme cold?
• Can parking spaces be easily delineated?
• Do you need a specially trained installer?
• Does the area require snow plowing?
• What are the regular maintenance needs of the specific technology and product?
• Will the area beneath the surface need to be accessed for maintenance?
• What is the guarantee of the product?
• How quickly is the product installed? Are there restrictions based on weather?
• What type of locking system holds individual segments together?
• How permeable is the product? What is the infiltration rate?
• Is the product ADA compliant? Are high heeled shoes a problem?
• What if the land usage needs change? Can the product be reused? Recycled?

Porous or pervious concrete and asphalt products look similar to their traditional counterparts. However, they are constructed in such a way that they have high porosity allowing water to freely pass through.

Unit interlocking pavers are commonly seen in a wide variety of projects throughout North America. They are very popular and provide a beautiful design element to projects. The concept behind the permeability of this product line is two-fold. The pavers are installed using the joints and spaces between individual pavers as the infiltration areas of the surface. The larger and more open the spaces are, the more permeable the surface. In addition, there are also products on the market in which the actual paving stones are permeable, thus increasing the infiltration rate that much more.

As one of the first available permeable products, concrete permeable pavers can be seen throughout North America for uses such as ground stabilization and access areas.

Flexible porous plastic pavers are gaining acceptance as a truly sustainable permeable paving technology. These types of pavers are most commonly manufactured using recycled plastics, an additional dimension to the sustainable aspect of the product. The pavers are designed with a matrix of open cells that can be filled with gravel, grass or different green ground covers. The grid cells contain the fill, eliminating all migration and compaction and ensure the ground retains its permeability. Flexible plastic porous pavers can also be used to reinforce ground surfaces such as gravel and grass to provide a stable ADA compliant surface.  There are wide variations of quality, strength, design and durability within this category and it is important to fully investigate each product to ensure the correct product is chosen for the specific application.

Change can be daunting. As mentioned, permeable paving technologies have been widely and successfully incorporated into European designs for decades. They have gone a step further and use canopies of solar panels as protective covers atop surfaces of permeable alternatives.

Initial cost savings associated with the incorporating of permeable paving are very attractive, more so with the impended changes to the storm water tax structure and the need to reduced sealed ground surfaces.

It is up to us to include sustainable, long lasting and environmentally sensitive designs and technologies into our projects to ensure we leave a legacy for future generations that includes clean water and a healthy earth ecosystem. 

Ellise Gasner is a native Torontonian. She currently works for Purus North America in Business Development. She is excited to be involved in bring sustainable practices to the foreground and ensuring that we all do our part to leave the world healthy and environmentally sound for generations to come.